199,290 views
16 votes
16 votes
A culture started with 6000 becteria. after 4 hours it grew to 6600 becteria. Predict how many bacteria will be present after 10 hours. Round your answer to the nearest whole number. p=ae^kt

User Spirytus
by
3.0k points

1 Answer

24 votes
24 votes

Answer:

7614

Explanation:

The exponential growth of the bacteria culture can be modeled by the equation ...

p = a·b^(t/c)

where 'a' is the initial population, 'b' is the growth factor, and 'c' is the period over which that growth factor applies.

__

model

In the given scenario, we have ...

  • a = 6000 bacteria
  • b = 6600/6000 = 1.1 . . . . growth factor
  • c = 4 hours

So, our model is ...

p = 6000·1.1^(t/4)

__

application

After 10 hours, the population is predicted to be ...

p = 6000·1.1^(10/4) ≈ 7614

We predict 7614 bacteria will be present after 10 hours.

__

Additional comment

If we compare the form we used to the one suggested in the proglem statement, we see

  • p = 6000·1.1^(t/4)
  • p = 6000·e^(kt)

For the bases of the exponential term to be the same, we must have ...

1.1^(t/4) = e^(kt)

(1.1^(1/4))^t = (e^k)^t . . . . . factor t from the exponent

1.1^(1/4) = e^k . . . . . . . match the bases

k = ln(1.1)/4 . . . . . take natural logs

k ≈ 0.0238275

and the equation becomes ...

p = 6000·e^(0.0238275t)

__

In terms of 'a', 'b', and 'c' used above, we find ...

k = ln(b)/c

User Rajshekar Reddy
by
2.9k points